Telephone system



July 24, 1928. 1,678,185

8 rR. w. HARPER 'TELEPHONE SYSTEM 2 Shasta-Sheet l EN??? 'WW Patented July 24, 1928.

- UNITED STA TES PATENT OFFics.

ROBERT-w. HARPER, or EAs'r, ORANGE, NEW JERSEY, AssiGivOR TOQRELL TELEPHONE LABORATORIES, iNooRroRArEn, OE NEW YORK, N. Y., A CORPORATION OF/NEW YORK.

Application ined my 1s,

This invention relates to automatic telephone exchanges and its object is to improve systems for restricting the service given to telephone lines.

. A 'feature oi this invention is a system in which cert-ain subscribers lines, when at tempting to make` calls over a restricted group of trunks, cause the finder switch, by reason oi' their particular location therein, to so aiiect the selector switch that when operated by the calling subscriber to select said group ot trunks it will automatically refuse to seize any one of them although idle. n

Other aspects and advantage-s of the invention will appear fully from the following description and claims. n

In the drawing, comprising two4 sheets,` Fig. 1 illustrates a line iinder of the type `generally known asthe Strowger stcp-by-step switch and two subscribers lines.

Fig. 2 shows the first selector switch.V At the bottom oi' this figure isshown a controlling circuit :tor a number of line wfinder switches. l

The line finder switch F is of vthe, step-by-v step type `having` a capacity `for 200 subscribers lines. The group or' 200 lines is divided into two parts, 100 lines appearing in the bank 108 and the other 100 lines appear'- ing in the bank 109. `The sleeve or test conductors oit' the entire 200 lines appear in a third bank 110. The` switch has twor sets of tip and ring brushes mounted yonwthe saine shaft, the set 105 havingaccess tothe ten levels of contacts in the bank 108y and the set 106 likewise. having access to the contacts in y the bank 109. The switch also has a pairoi test brushes 107, one for each group 01.100, mounted on the shaft and cooperating with the test bank 110.

Moreover, the switch is provided with a row of group selecting` commutator segments 123 anda brush 125 for stopping the linder in its vertical moveinent when it has reached the level containing` the calling line. y,

LThe iinder switch is also equipped ywith a second coininutator 124 which has la segment igor eachL vertical group selecting position ot the switch together with va cooperating brush 126. Byconnecting the different segments of the commutator 124to ground, theugroup of 20 subscribers lines corresponding to a grounded segment is restricted as to service. The subscribers lines 100 and 101, are seen to appear 'in corresponding `levels of the l TELEPHONE SYSTEM. if

1927. serial No. 192,176.

respective banks 10S and 109. The line`100 and nine other lines comprise a level oi' 10 lines inthe bank 108, whereas the line 101 and nine others comprise the corresponding 10 lines in the bank 109. These 20 lines comprise a group, and iany one of them in calling operates the group relay 104 to initiate the movementofV aline finder switch.

In Fig. 2 the selector switch S has access to groups or levels of trunks, some of which levels are restricted to certain groups `of subscribers. To effect the restriction, the selectory has an auxiliary switch 21.07 which closes whenever ar subscriber positions the switch S opposite a predetermined group of cuit for this purpose may be traced from battery, through the winding of the cutfoii' relay 103 and in parallel from the battery through the resistance 128 and thence through the inner contacts ot' relay 102, con- -ductor 129 tothe terminal 127. Relay 104 y places ground potential on the corresponding commutator segment 130. Relay 104 also closes ythe start wire to set the finder switch F in Operation, assuming this to be the first idle switch. `The startwire may betraced froni ground, through the outer left contact of relay 214, conductor 221, through theup'- per contact of group relay 104, conductor 131, thencethrough the normal rightcontact of relay 115, winding of thestartrelay116 .to battery. Relay 116 `Operates and at its inr ner left contact applies ground potential to the sleeve'conductor 122 of thetrunk 121. Relay 116 also closes an operating circuitior relayv 114 traceable from ground, through the outer right contact` of relay 116, conductor 132, normal contact of the vertical. magnet y119, right contact of the rotary magnet 118, left winding of relay 114, to battery atthe outerleft contact of relay 11:5. Relay 114 closes a circuit orthe vertical magnet '119 which may be traced from battery, through also opens the circuit ot' relay 114 which ree I leases, in turn opening the circuit' of rthe magnet which also releases. f The magnet o-n releasing recloses the circuit of relay 114 which operates and again operates the rinagnet; This process continues until the switch reaches the group containing the calling line.

Since, in the case assumed,ft h'e calling line C 100 appears in the first group or level, the

test circuit is completed at the end of the first vertical step. and maybe traced `from ground, over the segment- 130,-brush 125, lett winding of relay 112, armature yand frontcontact of magnet 119, contact of magnet' 118,V lett winding of relay 114, to battery atthe left contact of relay 115. r1`his circuit operates the relay112 and holds the relay 114 and the magnet 119 energized to preventt'urther stepping. Relay 112 is slow to operatefin order to provide an` interval betweeny the vertical and rotary movements ofthe switch.'

Relay 112 when operated locks in lcircuit from ground, over the outer right contact et relay 116, Contact and right winding `of relay 112, winding ot the magnet 119, to battery at the contact of relay 11 Then relay 112 fully operatesa circuitis closed for the rotary magnet 118 traceable from battery, through the winding of said magnet, outer rightI frontl contact 'of relay 112, contact of relay 114 to the, grounded conductor 132. The magnet 118 advances the brushes on to the first set of terminals *in the group and also opens the ,circuit ot relay 114.

Relay 114 releases, in turn releasing the magnet 118. Magnet 118 recloses the circuit ot relay 114 which operates and recloses the circuit of the magnet. This process continues until the lower brush 107 reaches the calling line. When the calling line is reached, the test circuit is closed from grounded conductor 132, right Winding of relay 114, lnormal right Contact of test relay 113, inner right back contact-,ot test relay; 111, lett winding ot relay 113, lower test brush 107 to battery on the test terminal 127. Relay 113 operates in this` circuit and relay .114 remains ener-y gized to prevent further operation of the magnet 118. Relay 113 operatesl the relay 111 4in a circuit from battery, throughthe left Winding of relay 111, inner left Contact of relay 113, outer left front contact of relay 116, conductor 133 to ground through the vertical oft normal springs 120; These o springs are operated to their alternate positions on the first vert-ical step yor the brush shaft. Relay 111 in operating completes an operating circuit for Arelay V115. This circuit may be traced from battery,

through the lett Winding of relay 115, outer right front contact of relay 111 to ground on conductor 133. Relay 111 locks in a'circuit from battery, through its left winding and contact, inner left contact of relay 115, to ground on conductor 122. LRelay 113A locks temporarily in a circuit fromk battery, throughits right winding and contact, inner ylefty front contact of relay 112, to the grounded conductor 134. n

Relay-115 in operating releases the relay 116, but before relay 116 can retract itsarlmatures to remove ground from conductor 122 a substitute ground is placed on said conductor from'theselector switch S. Vith relays 113 and 111 operated, the calling line 100 is extended over the tip and ring conductors/of; trunk 121, through the' upper back` contacts of relay 209 and the windings of the impulse relay 200 to battery and ground. Relay 200 operates and closes an obvious circuit for slow relay 201 which operates and a lies Oround )otential to the sleeve conductor 122.r The'gro'unded sleeve conductory 122is also extendedi through the middle left front contact of relay "115, outer right 'ront contact of relay1`13, lower test brush 107, thence to battery through the winding otk the cut-oit relay 103.r Relay 103 operates and opens the circuit ofthe line relay 102. Before the relay 102 can release, however, relay 103'locls through its outer right contact to the grounded conductor 129. Relay 115 at `its outer lett armature opens the holding circuit of the magnet 119 and relay 112. vVhen cordance with the irst digit ot the called number.v At each interruption olf the line, relay 200 releases and closes a 'circu'it from ground, through the lower contact` of relay 209,`back contact ot relay 2,00, outer front Contact of relay 201, winding of slow release relay 202,' winding of the vertical stepping magnet 204 to battery. lVIa-gnet 204 operates to step the brushes 211 oppositethe tiret level y 'of terminals. Nhen relay y202 operates and when the shaft talresits first step to shift the rott-normal springs 207 a circuit is closed yfrom battery y203, springs 207, frontcontact o1 relay 202 through the winding otrelay to the grounded conductor 122. f

- At the end of the first series .of impulses, c

the brushes 211 have been driven to a given group of trunks which,fas assumed, Iare not restrictedto they calling subscriber. yAccordingly, the switch 210 is open with the brush shattstanding in thisl position.k After relay 112 releases, the holding circuit of re`- 207, contact of the rotaryvmagnet 205, lett an interval following the vtiret series of impulses, relay` 202 releases and opensthe originaloperating circuit for relay 203. Relay 203 is held,vhowever,in acircuit from battery, through itswinding, oil-normal springs `magnet 205 rotates the brushes to, the first set vol terminals in the'level and at its right contact opens the holding circuit of relay `203. The relay releases, in turn releasing the magnet 205. It the first trunk is busy, relay 203 reoperates in a circuit over the springs 207, contactfoil the inagnet205, upper set ot `springs S, inner lower baclr cont-act or re- `lay 200, conductor 223, to 'the busy sleeve ternfnnah Relay 203 again closes the circuit of the motor magnet 205-and the switch taires another step. This procedure continues until an-idle trunk :is found having no ground potential on the sleeve terminal. During the stepping movement of the switch,

s a circuit in parallel tothe test circuit isclosed through the winding o1' relay 209 to the grounded conductor 122. 11s long as busy trunks are encountered, relay 209 is shunted and docs not operate. lVlieinhoivever, an idle trunlr is found, the shunt-being removed,

relay 200 operates and closes the talking conductors of the trunk 121 through to the vbrushes of the switch S. Due to the resistance of relay 209, the; relay 203` does not operate. RelayA 209 releases the relay 200 `which opens thecircuit of relay 201. Before relayV 201 can release ground is returned over 'the sleeve conductor from the switch beyond to hold the relay 200 and to maintain ground potential on the sleeve conductor 122.

Other switches may be positioned to complete the extension oi: the connection inany well known manner. .i

When it is desired to release the connection, ground potential is removed `from the sleeve conductor 122 causing the release of relay 209. Thereleasemagnet 206 is operated in a circuit through its winding, springs 207 back contacts ot relays 201, 200 and 209 to ground. Magnet 206 restores the selector S which, on reaching its normal position, shifts the springs 207 to open the circuitvof magnet 206,

The removal of ground potential 'from conductor 122 releases relay 111. Relay 111 operates the release magnet 117 in a circuit from battery, through said magnet, springs 120, outer leftr contact ofrelay112, outer right contact of relay 111, left back contact of relay 116, to the grounded conductor 133.

Magnet 117 restores the finder switch F to normal, in which position the springs 120 to the windings are shifted and the circuit of magnet 1117 opened.` The shitting ofvsprings 120 also opens the, holding circuit o1' 115.` n c, l

Next it will be assumed that the subscriber atA substation A` `attemptsto extend a connection over a restricted group iof trunlrs. The line finder and selector switch are operated in the same manner as already explained with the exception that the selecto-r S` on being positioned opposite therestricted group closes the switch 21,0 at the end of the vertical movement. ylVitli switch 210 closed and with the brush 126 eneaging relays 113 and the grounded segment 135, a circuit may be traced 'from ground over brush 126, conductor 136, contactv 210 to the sleeve conductor Ground potential on the sleeve conductor 223 automatically renders all trunks in the level non-selective. The `s. 7itch, there-- fore, rotates `over the entire group to its 11th rotary position where the springs 203 are shifted. rPhe busy tone sourcel 2211 is connected `in a circuit over the springs 20,8 ot relay 200ingseries with the calling line. A tone is sent back to the subscriber notifyinghim thatthe connection cannot be obtained. s f

Had the call originated at the substation B, the linder would have operated in substantially the saine manner except 'that the .test circuit through the upper brush 107 is Fig. 2. Normally the relays 212 and'213 are `both operated overthe back contact of one or niorerelays similar to relay 115. In case battery or ground potential accidentally appearson the start conductor, either the relay 212 or 213 is released according to the nature of the trouble. With either ot these relays released, and the other relay energized, an obvious circuit is completed for lighting the lamp 216.

I a permanent ground potential is applied to the start wire, each finder will be started in operation and relay individual to each finder is energized 4and locked in a circuit from battery, through the contact of relay 220, right winding and front contact of relay 115 to the grounded start wire 131.

When all iinders have been operated, the` circuit ot relays 212 and 213 is opened and both of these relays release. A circuit is now completed over the back contacts of relays 213 and'212 for the relay 2111. Relay 2141 opens the start wire 221 and operates the relay 215 in a circuit from battery, through the winding of the latter relay, contact of relay 214-, thence to the grounded start conductor 131. Relay 215 operates the relay 218 which 10ers to the lrey 219, Relay v21.8

` also lights the lamp Q17 as avsignal and com* pletes a circuit for relay v220. Relay 220".` opens the holding circuit'of all relays 115.

That is claimed. is: v, l 1.7Ina telephone system,` a line finder having lgroups of terminals, lines appearing in said terminals,I groups 'of trunks, a selector having access to said trunks, `means for operating the inder yto extend a calling line tosaid selector, means for operating the selector to select a group of trunks and to seize an idle one, an ai'iXiliary lswitchdriven b said -finder and closed in certain group selecting positions thereof, and means'A controlled by the auXilary switch for render- -ing said selector ineliective to seize an idle trunk. v y n In a ytelephone',system, a line linder, a

plurality of groups of lines appearing in said finder, groups of trunks, ak selector, means oroperating the finder to extend a calling line to said selector, means for oper-4 ating the selector to Choose a group` ot trunks n and toseiZe an idle one, an auxiliary switch mounted on the brush shaft otvsaid finder aiidfclosed incertain group selecting positions thereof, and iheans controlled by said auxiliary switch for rendering the selector switch ineffective to seize an idle trunk.

In4 combination, a line iinder switch, groups of subscribers" lines appearing in saidyswitch,a selector switch, groups of trunks, means for operating the finder to extend a calling line to the selector switch,

means controlled b` the ,calling subscriber for' actuating the se "ec'to'r to choose a desired group of trunks, means for operating the selector automatically to seize an idle` trunk in the group, a group vcommutator associated with the finder switch, and means controlled the subscriber for operating the switch,

means controlled byfa subscriber for operattorender the selector iiieiective to A here, 165

by the 'commutator if'kbll@ 'Ca/lling une api" pearsin a certain group for rendering the trunks of the' desired group non-selective.

4.111 combination, a primary switch,

groups of lines appearing therein, `groups of trunks, afselector, means controlled by n primary switch and selector to 'extend his line inthe directionot a desired group ot trunks, an auxiliary switch driven bythe primary switch, and means controlled bysaid auxiliary switch and dependent on the group of trunks chosen by the 4selectorto render .thev l selector ineffective tofseiz'e an idle'trunk. A

5. In atelephone system, a lline finder hav.-

ing llevels of' lines appearing therein,y groups of trunks, a selector switch, means controlled j by a calling subscriber for operatinglthe line ingl the finder and selector to extend the'calling `line to a` chosen group of trunks, a comf n'iutator and acircuit closed thereby whenlever the'l'nder'chooses'any line in a given group, and means controlled by said circuit seize any idle trunk incertain groups, y

lnwitn'ess whereof, I hereunto subscribe ROBERT w. HAnriiR.

rny'name this 28th. day of April, A. D. 1927. 

